Brain's face recognition area grows much bigger as we get older

If you feel overwhelmed by an ever-growing social circle, fear not. Your brain can keep up with all those new faces, thanks to one region that continues to grow even in adulthood.

The discovery is surprising, because most changes to the brain as it matures involve the altering of existing connections between neurons. But brain scans have revealed that one area of the cortex, the fusiform gyrus, gets much larger as we age.

The fusiform gyrus is thought to play a role in recognising faces, something that adults are better at doing than children. Brain scans of 47 people of different ages found – after taking into account the differing overall sizes of their brains – that adults had 12.6 per cent more solid brain matter in this area than children did.

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“What’s surprising here is that the changes involve a different mechanism, expansion not pruning,” says Kalanit Grill-Spector at the Stanford University School of Medicine in California, whose team made the discovery.<

It is thought that almost all brain remodelling occurs during infancy, childhood and adolescence, but surprisingly, this expansion of the fusiform gyrus seems to happen later in life, says Grill-Spector.

Uniquely human

Grill-Spector says that the changes seen in the fusiform gyrus are probably unique to humans, and may reflect the importance of facial recognition in our lives, especially during the time we become adults. “We’re constantly increasing our social circles. By the time we’re in college or high school, we know thousands of people,” she says. “Then we continue to learn new faces throughout life.”

The team compared the growth of the face recognition region with a different area, responsible for recognising places. The latter area remained identical in size across all ages.

“Our earlier work has shown that place and object recognition develop much earlier [than face recognition]. But facial recognition continues throughout adolescence and is a very difficult recognition problem, because it relies on spotting only small differences in facial changes to tell people apart,” says Grill-Spector.

Most other changes to the brain that take place throughout our lives, such as during adolescence and pregnancy, involve pruning the connections between neurons. “The role of pruning has received a lot of attention, but these new results show that tissue proliferation plays a role in fine-tuning of the cortex,” says Brad Duchaine at Dartmouth College, New Hampshire.

Inadequate growth of the brain’s face recognition areas might contribute to autism, Duchaine suggests, as well as conditions that make people unable to recognise faces.